Difference between revisions of "Minutes-11-17-2011"

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== Production ==
 
== Production ==
  
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- Dave: second cell of the second package was installed.   (Chris will do it tomorrow). Cathodes for the third cell also ready, working on the fourth cell cathodes. Third wire plane was strung and wires glued and soldered. The HV caps were replaced on the fourth, but we have problems so far with the dark current there; may require additional change of some capacitors. The fifth wire frame was laminated today. Problems with field wire spools, Dave will discuss it with Steve Christo from Hall B.  
+
- Dave: second cell of the second package was installed. Third wire plane will be populated tomorrow by Chris and we will try to install the third cell by the end of the day. Working on the fourth and fifth cell cathodes. The fourth wire frame on which Dave replaced the caps, is being tested with HV by Anatoly (see below). It delayed the wire stringing by one week so far. The fifth wire frames was laminated.  
  
−
- Lubomir: The installation of the first cell was much easier due to the new hubs/pins Bill designed. Flushing with gas since Tuesday, chamber is very tight (bubbles at as low as 15 ccpm). Setting HV on it was also easy. Vladimir tested all the channels with a scope and 55Fe: all working fine. But again, we see a noise at the same place (around HV trace on the fourth +HV sector) we saw on three cells in the first package, this time with higher frequency (~2.5 kHz). Will rotate the top cathode by 30deg after the meeting  to make sure we have the same problem here.
+
- Discussions about the noise coming from a HV trace initiated by Eugene. We know the noise is coming from a HV trace on the back of the PCB. The amplitude of the noise is close to that of the standard signals, but is random with a frequency of <3kHz and width of ~20ns. So, the probability for interfering with the signals is <0.3% say for 1us window, so negligible. Starting with the sixth wire frame we are going to apply additional conformal coating (like the green coating on the PCBs) on the four HV traces.
 +
 
 +
- Lubomir about the HV cap tests on the fourth wire frame: after replacing the caps last week and some conditioning we were able to get leakage current of 100-300nA initially but it later increased up to several uA. Anatoly replaced/fixed ~10 caps and the current went down to few tens of nA but still it was increasing after that. Normally, the initial current is high and then it goes down, opposite to what we see with this frame. This is the second frame on which we use 3kV rated caps and we had no issues like this with the first one. Also, Anatoly tested 37 of these 3kV caps separately and they didn't show such increase of the current with the time. Eugene: if the problem is in the 3kV caps we better wait for the 4kV capacitors (will have them hopefully in January!). We decided to continue with the HV tets: leave the frame under HV overnight and see if it will stabilize, then tomorrow morning will decide if we want to replace all the caps once more and then do more tests over the weekend. Then finally on Monday we should be in a position to decide if we will wait for the 4kV capacitors.
  
 
== Engineering ==
 
== Engineering ==

Revision as of 19:16, 17 November 2011

November 17, 2011 FDC meeting

Agenda

  1. Production Construction Tracking (Dave)
    • Production update
    • Second package tests (Lubomir)
  2. Engineering update (Bill)
  3. Electronics update (Chris)
  4. TDR (Lubomir)
  5. Other


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